Step1: Do remove all the unwanted softwares from computer
Step2: Run Ccleaner or TFC to remove junk files. You can download these from our tools page: http://www.techsupportall.com/tools
Step3: After that take backup of your download & documents folder from C: to another drive. Here is some path where all these folders are located.
C:\Users\User(Your user name)\Downloads
C:\Users\User(Your user name)\Documents
C:\Users\User(Your user name)\Desktop
After backup, do remove all the unwanted files & folder from there.
Please let us know if need more help regarding this.
Thanks